Here's what happens when you try to use last year's Smart Cover on the new iPad Pro

The latest iPad Pro is the same size as previous iPads, but users who are upgrading will discover that their old Apple Smart Covers won't work with their new iPad.

In fact, Apple is selling two different versions of the Smart Cover — one designed for the iPad Air 2 for $39, and another for the new 9.7-inch iPad Pro for $49.

The two covers are mostly identical. But a video posted by Nick Rodriguez, and spotted by Mac Kung Fu, shows that if you try to use the less expensive iPad Air 2 cover on a new iPad Pro, the old smart cover will float above the tablet's screen.

The reason why is that Apple slightly moved the magnets built into the new iPad Pro, moving the magnets just far enough away from their old location to make last year's Smart Cover float above this year's 9.7-inch iPad Pro.

The subtle Smart Cover change isn't because of planned obsolescence.

It's because Apple had to move the magnets inside the new 9.7-inch iPad Pro because the device has a new connector that allows users to attach Apple's Smart Keyboard cover, according to an Apple spokesperson.